1. Field of the Invention
The present invention relates generally to a device for controlling the operation of a plurality of printers operating in tandem with a recording medium being printed first by one of the printers and then by following ones of the printers.
2. Description of the Related Art
European Patent Application No. 0,154,695 and corresponding U.S. Pat. No. 4,609,279 disclose a laser printing system for either multi-color or verso printing. The disclosed laser printing system includes a plurality of devices arranged in succession which are simultaneously operated, wherein a recording medium emerges from the paper exit region of a preceding device and is supplied to a paper entry region of a following device, which may be a printer or fixing device. Between the two devices is a switchable deflection means for the recording medium or paper web. It is, thus, possible to provide modular construction of individual fixing modules and printing modules for combination with one another to form the individual devices wherein at least one fixing module follows a plurality of printing modules.
German Pat. OS No. 33 24 996 and corresponding U.S. Pat. No. 4,579,446 discloses a printer device for electrophotographic operation that is suitable for both recto and verso printing. Two individual devices are coupled to one another with a sheet turning mechanism arranged therebetween. First, a paper sheet is printed on the recto, or front, side with the first device, after which the paper is turned by the paper turning mechanism and is printed on the verso, or back, side with the following device.
When such printers are operated in a tandem mode, a significant problem arises in providing synchronous drive.
From German Pat. OS No. 33 24 996, it is known to provide a central common control unit to drive two devices, wherein the control unit includes page memories for every individual device in which image information to be printed is stored. The corresponding allocation of the image information into the individual devices is performed by a reversing circuit.
The known central driving unit for all devices is relatively complicated in construction. Moreover, when a central drive unit is used for high speed printers, the processing speed and power of the control unit has to be extremely great due to the high data rates, the complexity of page editing, and the necessity of generating an output in real time to the printers being controlled.
A laser printer is disclosed in U.S. Pat. No. 4,311,723.